ESPE2022 Poster Category 1 Growth and Syndromes (85 abstracts)
Background: Bone age (BA) is commonly used in pediatrics to define skeletal maturity for medical and non-medical purposes. Normal range is represented by 2 standard deviations (SDs) above and below the mean. A BA greater than ±2 SDs from the chronological age (CA) is considered abnormal. BA in achondroplasia (ACH) has not been fully characterized; calculation is challenging given difficulties in comparing x-rays with standard radiographs if using the Greulich-Pyle (G&P) method and complexity of using the Tanner Whitehouse method. Few publications have described delays in BA in children with ACH. One study showed a delay of 1.4 years for males and 1.2 years for females, with a difference between CA and RUS (radius, ulna, short bones) BA of 0.9±1.1 for children <10 years and 1.6±0.9 for those >10 years of age. Another study described a mean delay in BA of 11.6 months for boys and 8.2 months for girls during early childhood. Here we describe BA at baseline in a group of children participating in the Phase 2 dose-finding PROPEL2 study evaluating the preliminary safety and efficacy of infigratinib in children with ACH.
Methods: Left-hand radiographs of 37 children with ACH (age 7.9±2.1 years; female n=25; Tanner stage 1) were evaluated for BA by a single reader using the RUS method (TW2). BA relation to CA was expressed as BA/CA and BA-CA overall and by sex. SD score (SDS) was calculated using SD data from G&P atlas.
Results: The mean±SD BA was 8.2±2.5 years (no difference vs the CA; P=0.1). BA/CA was 1.06±0.24 and BA-CA was 0.37±1.4 years. Mean±SD BA/CA was 1.12±0.23 in females and 0.93±0.22 in males, a statistically significant difference (P=0.026). Six children (16.2%; 5 female, 1 male) had a BA >+2 SDs for age and sex, indicating an advanced BA compared with CA. Four children (10.8%; 1 female, 3 male) had a BA that was delayed compared with CA (≥ 2 SDs for age and sex).
Conclusion: This analysis did not confirm previous findings suggesting a delay in BA in pre-pubertal children with ACH. BA in females was more advanced than in males in this study, but within the expected variability for the age group. This work suggests that BA estimation in children with ACH can be employed for the same purposes as in children without skeletal dysplasia.
15 Sep 2022 - 17 Sep 2022